The moisture that occurs or develops in the foot area is necessary and healthful; however it is also uncomfortable, in excess. On average, after a foot is in a shoe for 10 minutes, the temperature in the shoe will reach approximately 105 degrees Fahrenheit. Moreover, in a typical day, a foot in a dress shoe may produce 2-4 ounces of moisture inside the shoe. Currently it has been the practice to rely upon hydrophobic (i.e. non absorbent) yarn worn against the skin to remove moisture away from the skin. Hydrophobic yarns consisting of synthetic resinous material (petroleum based) are non-absorbent, and can result in an uncomfortably wet sock condition underfoot due to impeded air flow and heat retentive characteristics of the yarn. In contrast, the typical dress or sport casual sock is formed entirely of hydrophilic (i.e., absorbent) yarn, such as cotton or wool, to provide maximum comfort. However, the hydrophilic yarn retains the moisture rather than removing he moisture away from the skin. Thus, there is need for an improved sock in which moisture collection and disposition are better managed.
One such solution is provided by U.S. Pat. No. 4,898,007, entitled Moisture Management Sock issued to the same inventor as the present invention and is incorporated herein by reference. The '007 patent provides a sock construction utilizing a combination of hydrophilic and hydrophobic yarn zones. This construction is especially suited for athletic activities in which the wearers' foot generates a large amount of moisture that must be wicked and evaporated. In particular, the toe and heel portions are knit predominantly, or entirely, of hydrophilic yarn while the instep portion extending therebetween is knit of hydrophobic yarn so that moisture absorbed from the wearer's foot by the hydrophilic yarn in the toe portion is transferred by wicking action into the hydrophobic yarn in the instep portion and then to the leg portion to be evaporated therefrom.
However, the amount of hydrophobic yarn required still causes heat retention, especially for dress and sport casual applications. If too much hydrophobic yarn is used, the hydrophobic yarn will cause the foot to generate more moisture than the hydrophobic yarn can remove, and thus the sock becomes ineffective. Heat retention is especially problematic in dress shoes. Within the enclosed environment of a shoe there is very little air flow--even less in dress shoes as most athletic shoes are usually vented. Yet dress shoes are commonly worn for longer periods of time than athletic shoes. Thus, there is as great if not greater need for efficient moisture control in a dress or sport casual sock than an athletic sock.